1. Field of the Invention
This invention relates to a pressurized, gas insulated, high voltage switching installation having single or polyphase metal encapsulation in which the switchgear sections comprise several adjacent pressure tanks, partitioned off in a gastight manner, for accommodating high voltage switchgear and other current carrying parts.
2. Description of the Prior Art
Siemens-Zeitschrift 1966, no. 4, at pages 263 to 266, describes a high voltage switching installation in which single phase branches are separately encapsulated and three-phase bus bars are encapsulated together. Siemens Zeitschrift 1975, no. 11, at pages 723 to 732, describes a high voltage switching installation of this type with full, three-phase encapsulation.
In the prior art installations, the operating switchgear and current carrying parts are, as a rule, individually accommodated in a multiplicity of differently shaped tanks which are partitioned off and gastight and are, essentially, connected in series, following the line of the current path between the bus bar and the line or cable termination.
This results in a correspondingly large number of flange connections which must be gastight. Also, due to the design, expensive storage provisions must be made for the different tanks. In addition, difficulties are encountered in realizing different circuit diagrams for each section when this is required, since the possibilities of varying the arrangements of tanks or encapsulation sections are very limited. The possibility of making such variations is particularly limited in polyphase installations because the conductor arrangement precludes, for instance, arbitrary rotation of the equipment.
In contrast to the above mentioned installations, German Patent 952 019 shows the arrangement of all the switchgear and current carrying parts of a section in a single tank. This design, however, has the disadvantage that, in the event of trouble or of maintenance and inspection work in one section, the entire installation must be shut down. If an insulating means having a dielectric strength greater than that of air at atmospheric pressure is used, it is necessary to drain off the insulating medium, with the consequence that, unless the installation is shut down, there is danger of breakdowns occurring because of the small insulating spaces.
The catalog of the firm COQ, Utrecht, "Trisep Metal-Clad SF.sub.6 -Insulated Switchgear 110 kV to 245 kV", shows a three phase, high voltage switching installation in which a portion of the disconnect switches belonging to the bus bar is arranged in the bus bar tank and the other part is accommodated in the power circuit breaker tank. This structure has the disadvantage that, in the event of an arcing fault occurring in the power circuit breaker tank which leads, for instance, to a welding together of the disconnect switch contacts, the power circuit breaker and the equipment enclosed by the tank can be repaired only if the associated bus bar, i.e., an essential part of the installation, is taken out of operation. Since the bus bar must remain shut down at least for the duration of the repair of the disconnect switch, operational availability is reduced. This is particularly disadvantageous in installations with only one bus bar system.
In the prior art installation, the power circuit breaker is accommodated in a separate pressure tank which is partitioned off from the tank for current transformers, work grounding switches and equipment required on the terminal side by means of a disconnect switch which, like the bus bar disconnect switches, has a switching gap in the power circuit breaker housing and another, electrically series connected, disconnecting gap located in the tank for the current transformer, the work grounding switches and the equipment required on the terminal side. The operability of the disconnect switches is therefore always dependent on the state of two different gas spaces.
It is an object of the invention to provide a high voltage switching installation of the type mentioned above in which maximum operating availability is ensured with a minimum number of tanks or encapsulation section forms.